Needle-free injection systems provide an alternative to standard injectate delivery systems, which generally use a needle adapted to penetrate the outer surface of a target. Typically, needle-free injection systems are designed to eject the injectate, such as a liquid drug, from a chamber with sufficient pressure to allow the injectate to penetrate the target to the desired degree. For example, common applications for needle-free injection systems include delivering intradermal, subcutaneous and intramuscular injections into or through a recipient's skin. For each of these applications, the injectate must be ejected from the system with sufficient pressure to allow the injectate to penetrate the tough exterior dermal layers of the recipient's skin.
Examples of needle-free injection systems and components are found in U.S. Pat. Nos. 4,596,556, 4,790,824, 4,940,460, 4,941,880, 5,064,413, 5,312,335, 5,312,577, 5,383,851, 5,399,163, 5,503,627, 5,505,697, 5,520,639, 5,746,714, 5,782,802, 5,893,397, 5,993,412, 6,096,002, 6,132,395, 6,216,493, 6,264,629, 6,319,224, 6,383,168, 6,415,631, 6,471,669, 6,572,581, 6,585,685, 6,607,510, 6,641,554, 6,645,170, 6,648,850, 6,623,446, 6,676,630, 6,689,093 6,709,427, 6,716,190, 6,752,780, 6,752,781, 6,783,509, 6,935,384, 6,942,645, 6,979,310, 6,981,961, 7,056,300 and 7,156,823; U.S. Patent Application Publication No. 2006/0189927; and International Publication No. WO 00/72908, the disclosures of which are incorporated herein by reference, in their entirety and for all purposes.